For example, as disclosed in Japanese Patent Laid-Open Publication No. 2010-152722, in a conventional deposit process in depositing/withdrawing machines, first, bills inserted into a deposit/withdrawal slot are sequentially fed to a discriminator one by one to be discriminated there. If, in the discriminator, detected is an abnormal bill such as a bill getting close to another bill or being conveyed obliquely than allowed, or a counterfeit or damaged bill, then the abnormal bill is conveyed to the deposit/withdrawal slot. At this time, together with the abnormal bill, some bills following the abnormal bill are also conveyed to the deposit/withdrawal slot. In the deposit/withdrawal slot, there is no separator for differentiating between the bills inserted and not yet fed to the discriminator and the bills having passed the discriminator and then returned to the deposit/withdrawal slot. Therefore, the returned bills to the deposit/withdrawal slot will continuously be fed again to the discriminator without being discriminated from the other bills in the deposit/withdrawal slot.
For that reason, when, for example, a plurality of abnormal bills are contained in the bills inserted into the deposit/withdrawal slot, or even when only one abnormal bill is contained depending on how to transfer the bills in the depositing/withdrawing machine, there would remain a bill which is not subjected to discrimination by the discriminator. Such a bill will be returned to the deposit slot together with the abnormal bill before being discriminated by the discriminator.